A motor is known that includes a stator which generates a magnetic field, a movable member which takes out rotational energy and a housing which accommodates them. The stator used in such a motor includes a laminated core formed by laminating a plurality of metal plates to reduce an eddy-current loss and a winding wound on the laminated core. The laminated core of the stator is formed in such manner as described below (see patent literature 1).
Initially, a metal plate such as an electromagnetic steel plate is stamped to a form of the stator (substantially in a ring shape) by a stamping work to obtain a core piece. Then, a plurality of core pieces are laminated by caulking caulk parts respectively provided in the core pieces to form a block. A plurality of blocks formed in such a way are prepared.
At this time, since the metal plate has deviation in the thickness of the plate due to a rolling process, the thickness (a dimension in a direction of lamination) of the blocks respectively formed by laminating the core pieces stamped from the rolled metal plates is not uniform in the circumferential direction. Thus, to make uniform the thickness of the core as a final product in the circumferential direction, under a state that the blocks are respectively rotated by a prescribed angle, the blocks are laminated. Then, in boundary positions of the laminated blocks respectively, welding parts provided in a plurality of positions of the core pieces in the circumferential direction are welded mutually to form integrally the blocks, so that the laminated core is obtained.